This invention relates to plastic cap closures, specifically to an improved cap that will be used with threaded or non-threaded containers.
This invention uses the Double Cap concept of my xe2x80x9cMultiple Cap Seal for Containersxe2x80x9d U.S. Pat. No. 5,295,599 issued Mar. 22, 1994
Another area of this application relates to the wiping mechanism which was described in my Invention Disclosure xe2x80x9cScrew Cap with Sealing/Wiping Diaphragmxe2x80x9d dated Feb. 11, 1994 and a second version dated and filed Jan. 11, 1996 Disclosure Doc. 390080 with the Patent Office.
Another area relates to a one piece tethered cap and tube as described by my invention disclosure xe2x80x9cOne Piece Tamper Resistant Cap and Vialxe2x80x9d Disclosure Doc. No. 384710 dated Oct. 10,1995.
Screw cap vials for micro centrifuge tubes have been used the medical disposable industry for many years. Their continued acceptance comes from the fact that they provide the best leak proof design for centrifugation, heating and freezing of sample fluids. Their disadvantages are primarily due to the fact that they are individually molded and usually require the assembly of an O-ring or liner to increase the sealing caps effectiveness. The major problem relates to a cost issue, which makes this product (tube and cap) approximately 10 times the cost of an integrally molded cap micro centrifuge tube. Prior art has also demonstrated that thread seals alone are not dependable and the use of different materials in the construction of caps, seals and containers has caused leakage problems. This is due to the thermal expansion and contraction rates associated with different materials during testing and/or storage at high and low temperatures.
Another disadvantage of the prior art closures is the potential for contamination of not only the added O-ring elastomer used as a sealing ring in the cap but also the colorant used in the molding of the plastic closures. The fact that caps can also get misplaced or put back onto another vial by accident causes other contamination occurrences. This last problem has been addressed in the industry by the addition of a tethered strap to hold the cap to the tube with an additional part and increased cost. An example of this would be U.S. Pat. No. 4,753,358 by Virea which describes how this tether can be created as a separate piece and be used to hold the cap and tube together as a one piece assembly.
It is also known in the industry that chemical resistance of containers and closures is of the utmost importance. While most plastic assemblies are made from polypropylene or polyethylene, these materials still lack the chemical resistance and temperature requirements for all applications. It is known that TEFLON (registered trademark of Dupont) and its injection moldable grades (PFA, FEP, TEFZEL etc.) are far superior for these uses but that they lack the mechanical properties necessary to hold the close tolerance for these applications. This new invention helps to solve these and many more problems associated with the prior art.
Another problem arises when the fluid samples are required to be accessed in the same container many times over or when the caps must remain off for extended periods. In both cases the fluids are exposed to atmospheric air exchanges, which can cause contamination, evaporation, condensation and/or aging of the fluid sample, which can affect the accuracy of any analysis being conducted on the specimens. The new invention addressed these concerns by limiting air exchanges yet still allowing easy access to the fluid contents.
This invention also relates to closures that promote sterile air venting and filtering of the container without the use of secondary plugs or permeable membranes used to maintain equilibrium between atmosphere and the inside of the container as illustrated in U.S. Pat. Nos. 2,186,908 and 5,595,907. This is accomplished by injection molding small (i.e. 5 to 50 micron) textured air channel vents into the sealing surface of the closure and/or container.
This invention also relates to a one-piece tamper evident closure with tethered container. Unlike existing snap on, snap off or snap on, screw off tamper evident closures as taught by U.S. Pat. Nos. 5,190,178, 5,267,661, and 5,456,376 this invention has many advantages. The most apparent is the low cost one-piece injection molded assembly. By molding as one piece, no orientation of the cap to its mating sealing threads during assembly is required. It only requires a downward axial force to engage a sealing surface. There also will be no fit or sealing problems due to multi-cavity processing, material shrinkage and/or tolerance problems because the closure and its container are being molded in the same tool at the same time with the same material (i.e. lot no.) unlike existing art under the same exact processing parameters. (i. e.: time, pressure, heat, humidity, etc.)
In addition, this invention also addresses the similar problems found with fitments as described by U.S. Pat. Nos. 5,174,465 and 5,348,184 which have many deficiencies. Even though these closures are mechanically attached to their fitment during the molding process, they lack the integral tether to keep its potentially contaminated cap with its container after each use. They also include internal threads which are known in the medical industry to provide a means for capture of liquid particulates while also providing recesses for contaminants to solidify thus, effecting the sealing capability and contamination problems during re-use. Also the uses of tamper evident foil seals are used for added sealing capability that adds additional costs and labor to these closures.
In addition, most containers are accessed with the use of a standard disposable pipette tip that is attached to a hand held pipetter in the medical industry. In normal operation when the tip is inserted into the fluid and the precise amount of sample is drawn inside the tip for transportation to another location, there exists a thin film of residue fluid attached to the outside of the tip. This is due to the surface tension of the material used to manufacture the pipette tip and the fluid characteristic of the sample. Common practice in the industry suggests that the outside of these tips be wiped clean with a KIMWIPE tissue prior to the dispensing cycle. This however, causes the following problems: 1) Requires the contact and disposal of an additional product (i.e. tissue); 2) Puts the user at risk while transporting highly infectious or radioactive fluids; 3) Reduces the amount of specimen that can be analyzed; 4) Adds cost and additional time necessary to perform dispensing. Some manufactures have added silicone to the polypropylene tip material (i.e. siliconized pipette tips) at additional cost to help reduce this problem, but still have not eliminated it. The thin film that is left on the outside of the tip usually combines to form small fluid droplets and could:
Affect the accuracy of the calibrated sample if they combine with the precise volume that is being dispensed by the inside of the tip. This can occur if the tip touches the sides of the receiving container leaving its droplets to combine with the sample being transferred;
Droplets can fall from the tip while being transported in or out of the container;
Droplets can migrate to the tip""s dispensing end and combine with the precision amount of internal fluid to affect the dispensing accuracy;
Leads to cross-contamination or contamination in general, if any of the outside fluid were to contact any surface or thing (i.e. radioactive material or volatile fluids);
In applications where samples are very small and precious any additional fluid that would be wasted by being attached to the outside surface of the tip could become very costly and would allow fewer test specimens to be examined.
This new invention addresses all of these concerns by providing an injection molded wiper as part of the closure to eliminate any and all residue occurring during transferring of fluids during liquid pipetting.
Another recurring problem with micro centrifuge tubes is the requirement to filter aqueous samples for clarification, particulate removal and/or sample preparation prior to the liquid being dispensed into the tube for testing. Prior art suggests the use of an additional filter assembly as manufactured by Gelman or Fisher Scientific be installed into the tubes opening to act as a funnel filtering all incoming fluids before entering the container. After the container is filled, this filter assembly must then be discarded and the tube can then be capped for storage or further testing. This not only becomes time consuming but the additional filter assembly ads cost and potential problems with contamination and disposal. The new invention addresses these problems with a one-piece design.
Another problem arises when smaller more delicate tissue samples, used by histologists, are usually first put into small biopsy bags or separate open-mesh capsules then submersed into histological solvents, in a separate container, for storage. This new invention helps to reduce the number of parts and tasks associated with the technician""s labor hours and tissue handling time by creating a new storage closure that addresses these issues.
Accordingly, there is a need for a simple cap closure that addresses all of these problems by reducing the time necessary to perform these operations, minimize the contamination problems, prolongs sample life and reduces the manufacturing costs.
For a better understanding of the invention and how this new cap closure overcomes these disadvantages, reference is made to the following Summary, Preferred Embodiments, Detailed Description and Drawings.
Accordingly to the invention, the problems mentioned above are solved by cap closures that increase the effectiveness of sample containment and withdrawal at a reduced manufacturing cost.
The present invention provides for a threaded cap design that incorporates a pressure responsive diaphragm that increases the sealing effectiveness of the cap when the internal pressures of the container increase during testing or storage (i.e.: centrifugation, heating and freezing). As an improvement to xe2x80x9cSealing Cap for Containersxe2x80x9d U.S. Pat. No. 5,513,768, the cap and the container have seamless matting tapered surfaces which increases the sealing contact area as the closure is screwed onto the container and promotes an effective seal. Using the mechanical advantage of the threads to compress the tapered side walls of the caps convex sealing diaphragm, the interference between the cap and its container increases as the cap is rotated downward onto its final sealing position while bulging the convex sealing diaphragm outward. The increased tapered sealing area offers better sealing capability than the existing annular ring design that is common within the closure industry. It also offers a less expensive and better closure because of its one-piece design as compared to the caps that required an additional elastomer to make its seal and the contamination problems associated with it.
According to another aspect of invention, the threaded sealing cap has a hinged access top/locking cap which has a mating taper area designed to engage and seal to the inside surfaces of the convex diaphragm. This angular surface provides additional support while sandwiching the sealing diaphragm sidewall between it and the internal tapered sidewall of the container. The attached top can be molded with a finger tab for access or can be molded with a permanent snap lock to create a one piece convex sealing cap closure for those applications not requiring access other than by complete cap removal. This closure is adapted to high integrity sealing applications wherein complete sealing is required under a wide range of temperature and pressure range conditions.
In another variation, the access/locking cap can be incorporated as a separate molded part. This would allow for colorant to be used for this cap for identification or labeling purposes while maintaining only virgin material for the part, which may contact the fluid within the container. This eliminates the need for multiple stability evaluations in applications using colorant in caps while also allowing the use of standard automatic capping and unscrewing machines.
A further object of this invention is to incorporate the use of chemical and temperature resistant TEFLON fluorocarbon resin into the convex sealing diaphragm of the closure. This material, which inherently has mechanical problems with close tolerance parts due to cold flow and memory loss, requires additional support in applications such as these. This will be accomplished with the addition of a pre-formed back up spring, coil spring or compression of an elastomer O-ring that will exert constant radial pressure on the TEFLON seal insuring contact with the inside surface of the container (i.e. plastic, glass etc.) at all temperature and pressure variations. This becomes very important for those uses that require the use of chemically inert materials while also requiring large temperature variations during testing or storage. This closure is particularly adapted for cryogenic storage of organic samples.
Another object of this invention is to provide a low-cost, self-venting aerosol resistant closure. One particular area of concern is the reconstitution of toxic drugs, such as those used in chemotherapy. When diluent is added through a membrane or septum by a syringe needle, a positive pressure builds up in the sealed vial. Aerosols containing the reconstituted drug can be released when the septum is punctured and fluid is injected, exposing personnel to potential contamination. By incorporating a low cost injection molded aerosol resistant vent into the closure itself or the needle assembly, would help to prevent the release of any contaminated aerosols that would normally be released due to the increased pressure of the sealed container as is common in existing products. Many other venting applications exist for containers or filters that require gas exchange between the inside of the vessel while preserving sterility and preventing fluid leakage. Another object of the invention is to provide a closure of the above type that is also adapted to permit withdrawal of the sterile liquid by means of a hypodermic needle or pipette tip. Another application would be the use of the very small molded channels on the outside surface of a filter adapter that would fit between a hand-held pipetter and a disposable pipette tip. This adapter would prevent aerosols from the drawn fluid in the tip from contaminating the pipetter barrel. These small vent channels can be injection molded in the 3 to 50 micron size and produce much better filtering results than that described in my xe2x80x9cAerosol and Liquid Transfer Resistant Pipette Tip Apparatus and Methodxe2x80x9d U.S. Pat. No. 5,580,529 issued Dec. 3, 1996. This injection molded filtering concept can help to eliminate the need of an additional microporous membrane or filter material of the type made by Porex Corp. usually required in sterile venting applications such as these and many more.
Another object of this invention is to provide a cap with a flexible tether attached to a molded container as an all in one injection molded assembly. This would provide considerable cost savings over existing art that sometimes require three individual components (i.e.: cap, tube and tether) plus labor to accomplish the same end product. In a further embodiment the tether can be molded together with the tube with tamper resistant connecting ribs. In this embodiment the container could be filled with fluid, the cap and containers threads would be created with lead-in tapers on the top of the threaded profiles. This would allow the cap to be rotated about its tether and pushed directly downward over the threads to its furthest most sealing position without the need for cap rotation. This would simplify the filling cycle while also decreasing the time necessary for capping especially for automated equipment. To open the container, the user must now rotate the cap (unscrew) while also breaking the thin small tamper evident ribs connecting the attached tether to the container or cap, showing that the container has now been tampered with. The thin ribs could be designed with as few as one rib or multiple ribs depending on the requirements. In another variation, the user would break the contact rib or ribs prior to installing the cap onto the container. Another embodiment would be that the cap, tether and container was injection blow-molded in a one-piece assembly, the container would then be blown to a size larger than the original injection profile. This would allow larger containers to still incorporate the one-piece tether-cap design.
A further embodiment includes a tamper evident band, as part of the tether, which after assembly can be removed by use of a pull-tab, which breaks the thin rib or ribs that connect the tether to the container allowing the cap to be unscrewed. Another variation to secure the tamper evident closure to the container would be to form at least one projection on the locking wall of the container that engages a tamper evident ring during application. The ring or lower skirt is connected to the threaded upper skirt by means of a frangible section, which like the tethered pull-tab is removable by tearing and fracturing the frangible section. It is also understood the tamper evident ring could be molded to the containers locking wall with means for engagement to the upper skirt of the closure.
Unlike existing art, with separate cap and container, this invention incorporates the cap and container as one piece with a tether to insure the cap always stays with its container. This not only reduces cost but also allows the parts to be molded with much tighter tolerances especially in multi-cavity applications due to the fact that they are molded at the same time, using the same exact material under the same molding conditions. This also becomes very important in many high and low temperature applications where the thermal expansion of the material is exactly the same. These tethered embodiments could incorporate the new convex seal, wiping design, vented concept, filter design etc. or the standard threaded cap with liner if so desired.
In a variation of the above, the cap and tether with or without a tamper evident feature can be integrally molded to a threaded neck or fitment with a thin flange that can be attached to a separate polymer-coated paperboard container, plastic bag or other container constructions. This may be accomplished by welding the parts together or with the use of adhesive or other means of attachment known in the art. Because the fitment is unattached to its container at the time of molding, it then becomes possible to injection mold the closure directly over its mating threaded neck and assemble the two parts together with integral tether during the molding cycle with a straight axial downward force. In this position the closure cannot be unscrewed without breaking the tethers connecting rib or without removal of the tamper evident pull-tab.
In another variation, the fitment, cap and tether may also be molded in a one-piece open configuration that would allow the further addition of a molded in tamper evident diaphragm within the spout. This diaphragm would act much like a foil seal in prior art applications and would require removal by means of a tear tab or the like prior to accessing the contents of the container of which the fitment had been attached. However, unlike the foil seal, this removable diaphragm requires no secondary assembly or another part.
It is a further object of this invention to provide a closure with wiping mechanism for pipette tips which effectively removes all the liquid from the outside surface of the tip as it is withdrawn from the vial while still incorporating an access cap that can be resealed after use. More particularly, a one piece injection molded closure which incorporates a conical section with a spiral finger or fingers designed to resiliently expand and contract about a tubular conical pipette tip maintaining contact at all times with its outside surface while wiping and removing the fluid film or droplets from its surface. Again, it is difficult to compensate for the amount of fluid left behind clinging to the outside of the pipette tip because it varies by the nature of the fluid, its characteristics and more often by the technique of the person doing the pipetting. Even the most experienced technician will have inconsistencies because of interruptions that in effect can void test results. However, this wiping feature eliminates the above-mentioned problems while more importantly, saving time and increasing sample life.
The wiper section can be incorporated into my two cap design xe2x80x9cSealing Cap for Containersxe2x80x9d U.S. Pat. No. 5,513,768 by replacement of the sealing cap with a wiping cap design. This allows the user to first fill the container, then rotate the wiper cap into the container opening, and rotate the locking cap into the wiper opening, thus sealing and locking the container. To access the fluid, the locking cap must then be rotated outward; a pipetter with tip would then pass through the conical wiping fingers accessing the fluid within. Upon removal the wiping fingers would wipe and remove all the fluid that had attached itself to the outside surface of the tip while keeping it within the container. Unlike normal procedure, there would be no need to wipe clean the outside tip with tissue before transporting the sample. This feature also greatly reduces the amount of contamination that can occur while also saving precious fluid samples and time. It also helps to minimize air exchanges within the container by providing minimum size openings compared to open neck containers. This helps to reduce airborne contaminates from both entering and exiting the containers while also increasing the life of the fluid specimen due to evaporation or aging of the sample.
Another variation of this wiper design incorporates the use of a thermoplastic elastomer similar to that made by Monsanto Chemical Company under the Trademark SANTOPRENE. Using this rubber-like material allows the design freedom to injection mold a very thin wiping diaphragm with a small opening incorporated into the closure itself. As a one-piece assembly, the entry hold will expand and contract about the conical pipette tip while wiping the outside surface free of any liquids. By incorporating thickened wall sections for the threaded skirt and access cap area, the mechanical properties will increase thus giving more stability to the rubber-like material in the snap and threaded areas for this one piece injection molded closure. This unique material offers many advantages over hard plastic such as polypropylene or polyethylene that is commonly used in these closure applications. Another variation would be to injection mold this one-piece threaded skirt and access cap with a thin septum. This would allow aseptic injection of reagents or withdrawal of fluid without compromising sterility or integrity of the contents. This one-piece design, unlike existing art, could be used with or without the access cap for convenience especially in automated dispensing machines. It would also be beneficial to incorporate the venting aspect of this invention into either the cap or the container to encourage sterile venting when the fluid is accessed.
It is a still further object of this invention to provide a one-piece closure that would incorporate a molded-in screen type openings for straining or screening aqueous solutions before entering the container. A variation of this would be to sealably attach a woven monofilament screen (i.e.: polyester, polypropylene, TEFLON etc. from 5 microns and greater) to the cap for sterile pre-filtering of any solution containing particles. Another variation of this embodiment would include the addition of a hydrophilic, hydrophobic or oleophobic microporous filter membrane (i.e. .0.02 to 0.45 micron pore size) that would be sealably attached to the closure and be useful in sterilizing or clarifying biological samples by removing interfering particulates from blood, urine or other fluids that may be cause for inaccurate readings during analysis before they enter the container. Membranes can also be used to remove bacteria cells from media, DNA purification and filter any fluid. They can also be used to introduce a predetermined volume of dry reagents into the liquid sample causing a color change, reflectance or electrical conductivity. An example of this might be with the access cap open, a sample of urine or serum is dispensed into the cap cavity, it wets out and moves though the porous matrix and it solubilizes one or more reagents that have been previously deposited into the filter membrane bed volume and into the container. This would allow manufactures to ship its containers with pre-loaded reagents that would be required to complete an analysis or test requirements. Another variation would be to fill the cavity of the cap with dry reagents that would mix with the incoming fluid. This internal cavity when filled with dry reagents could also be made with a multitude of small openings that would hold the pelletized reagent but would mix thoroughly with the containers liquid when the cavity holding the reagents drop below the fluid level of the container. This mixing could occur by hand or with the use of an automated tube shaker. Another variation would be to incorporate a hydrophobic membrane into the cap, fill it with a pre-determined volume of fluid, seal the closure, fill the vial with a pre-determined volume of another fluid, when centrifuged, the two fluids would mix together. Sterile venting both the closures fluid compartment and vial become necessary to insure fluid flow during centrifugation.
Another variation using a hydrophobic membrane would be to fill this internal cavity with oxygen scavenging pellets such as AGELESS manufactured by Mitsubishi Gas Chemical Corp. or OXYGUARD by Toyo Selkan that would absorb oxygen from the gases contained within the headspace of the sealed tube or oxygen that may ingress into the container. This would prolong the life of oxygen-sensitive samples and decrease the aging effects associated with oxidation. Pellets of another type could also be used to absorb moisture that would be beneficial in the storage of dry materials when a hydrophilic filter membrane was used in the closure assembly.
It is also an object of this invention to create a simplified one-piece tissue storage container for use by histologists. By incorporating small openings into the cavity formed by the cap closure, you have created a storage vessel that can be used to hold tissue samples while being submersed into the fluid of the container. The samples can then be accessed through the access cap or can be withdrawn from its storage container by the complete removal of the threaded cap or screwed onto other containers for further evaluations.
The above is a brief description of some deficiencies in the prior art and advantages of the present invention. Other features, advantages and embodiments of the invention will be apparent to those skilled in the art from the following description, accompanying drawings and appended claims.